Semiconductor device and a method of manufacturing the same

ABSTRACT

To improve the connection reliability at the time of packaging a semiconductor device and to make the method management easy in a semiconductor device manufacturing method.  
     The semiconductor device comprises: a tub  1   e  for supporting a semiconductor chip  2;  a sealing body  3  formed by sealing the semiconductor chip 2 with a resin; a plurality of leads  1   a  made of a copper alloy, exposed to the back face  3   a  of the sealing body  3,  and having a soldered layer  8  on the exposed mounted face  1   d ; and wires  4  for connecting the pads  2   a  of the semiconductor chip  2  and the corresponding leads  1   a . In the manufacture method, the sealing body  3  is polished, after resin-molded, at its back face  3   a  with a brush to form the two widthwise edge portions, as exposed from the back face  3   a  of the sealing body  3,  of the lead  1   a  into rounded faces, and the mounted face  1   d  of the lead  1   a  including the rounded faces is protruded at its central portion from the back face  3   a  of the sealing body  3  thereby to improve the connection reliability at the packaging time.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a semiconductor manufacturingtechnique and, more particularly, to a technique which is effective whenapplied to an improvement in the connection reliability at the time ofmounting a surface mount type semiconductor device.

[0002] The technique to be explained has been examined by us when weinvestigated and completed the invention, as will be summarized in thefollowing.

[0003] One resin-sealed type semiconductor device, as intended to reducethe size, is exemplified by a semiconductor package called the “QFN”(Quad Flat Non-leaded Package).

[0004] The QFN is a surface mount in which a plurality of thin leadsarranged around a tub supporting a semiconductor chip are arranged onthe back face (i.e., the face on the semiconductor device mounting side)of a sealing body, and has a single-face molding structure which uses alead frame having only one resin-molded face.

[0005] In the QFN, the individual leads are arranged on the back face ofthe sealing body so that a packaging area (of the connecting region) hasbeen retained for mounting the leads with a solder on the mountsubstrate.

[0006] Therefore, the QFN is molded with a film sheet so that burrs(such as resin burr of a leakage resin or resin flush, as will be calledthe “resin burr”) of a molding resin may not be formed on the leads onthe back face of the sealing body (although this molding method will becalled the “laminate molding method”).

[0007] At the molding time, more specifically, the film sheet is held inclose contact with the back face of the sealing body in the cavity ofthe molding die, so that the resin burr may be prevented from stickingto the leads on the back face of the sealing body.

[0008] Here, the structure of the QFN is described, for example, onpages 56 and 57 of “Semiconductor Assembling/Testing Technique of '99,Extra Issue of 1998 of Monthly Semiconductor World 1998”, issued on Jul.27, 1998 by Kabushiki Gaisha PRESS JOURNAL”.

SUMMARY OF THE INVENTION

[0009] In the QFN of the technique thus far described, however, thestand-off height at the packaging time is made substantially as small asthe plated thickness by its structure. Therefore, the solder wettabilityat the QFN packaging time is seriously deteriorated if the resin burr isformed In the vicinity of the leads on the back face of the sealingbody.

[0010] In the QFN, moreover, leads 1 a may be deformed toward the sideof a semiconductor chip 2, as exemplified in the comparison of FIG. 19A,by the influence such as the resin charging pressure at the moldingtime. As in a QFN 25 of the comparison of 19B, a resin burr 16 such asthe resin flash is then easily formed on the lower side (or back side)of the deformed lead 1 a.

[0011] This resin burr 16 raises a problem that it can hardly be removedby the well-known deburring method such as the high-pressure watermethod or the liquid honing method.

[0012] In the semiconductor package having the single-face moldingstructure such as the QFN, on the other hand, the laminate moldingmethod may be performed. Even with this laminate molding method,however, it is difficult to eliminate the resin burr completely. Anotherproblem is that it takes a cost to make a modification into the laminatemolding apparatus.

[0013] Where the QFN is molded by the laminate molding method, moreover,the molding resin charged between the leads may be wrinkled to formprotrusions of the film sheet. These protrusions obstruct the leadclamping in the cutting die at the lead cutting time thereby to cause aproblem that the leads are cut to become defective.

[0014] Here at the lead cutting step, the leads are pressed and cutdownward (in the direction of the face on the side opposed to themounted face) by the cutting punch (or cutting blade). Then, the leadburr is formed on the lower side (or on the mounted side) of the leadsto cause the defective connection at the QFN packaging time thereby toraise a problem that the connection reliability is lowered.

[0015] On the other hand, the QFN is troubled by another problem thatthe materials of the individual components are deformed by the heat atthe working time so that they cannot retain their flatnesses.

[0016] In the manufacture of the QFN, there is another problem that thefacial pressure on the molding die has to be strictly managed so as toprevent the back face of the sealing body from having the resin burr.

[0017] At this time, another problem is that the molding die has to befrequently cleaned.

[0018] On the other hand, the technique for exposing the leads to theback face of the semiconductor device by polishing the back side isdescribed in Japanese Patent Laid-Open No. 195743/99 and 240940/90.However, the former has no description on the semiconductor devicehaving the single-face molding structure. The latter is directed to thetechnique for separating an integral lead into individual leads bypolishing the back face side of the semiconductor device, but does nothave any description on the semiconductor device in the state where theinner portions of the adjoining leads are separated in advance.

[0019] An object of the invention is to provide a semiconductor devicefor improving the connection reliability at a packaging time, and amethod of manufacturing the same.

[0020] Another object of the invention is to provide a semiconductordevice intended to facilitate the process management, and a method ofmanufacturing the same.

[0021] The aforementioned and other objects and novel features of theinvention will become apparent from the following description to be madewith reference to the accompanying drawings.

[0022] The representative of the invention disclosed herein will bebriefly described in the following.

[0023] According to an aspect of the invention, there is provided aresin-sealed type semiconductor device comprising: a tub for supportinga semiconductor chip; a sealing body formed by sealing the semiconductorchip with a resin; a plurality of leads arranged around the tub andexposed to the face of the sealing body on the semiconductor devicemounting side; and connecting members for connecting the surfaceelectrodes of the semiconductor chip and the corresponding ones of theleads. The two widthwise edge portions of each of the leads are formedof rounded faces, and the mounted face of the lead including the roundedfaces is protruded at its central portion from the face of the sealingbody on the semiconductor device mounting side.

[0024] According to another aspect of the invention, there is provided amethod of manufacturing a resin-sealed type semiconductor device,comprising the steps of: preparing a lead frame in which a plurality ofleads are arranged around a tub for supporting a semiconductor chip;bonding the tub and the semiconductor chip; connecting the surfaceelectrodes of the semiconductor chip and the corresponding ones of theleads by connecting members; forming a sealing body by resin-sealing thesemiconductor chip and the connecting members on the lead frame on thesemiconductor chip arranging side, to arrange the plurality of leads onthe face of the semiconductor device mounting side; exposing theplurality of leads by polishing the face of the sealing body on thesemiconductor device mounting side; and separating the plurality ofleads from the frame portion of the lead frame.

[0025] According to the invention, the connection regions of the leadsneeded at the time of mounting the semiconductor device on the mountsubstrate can be reliably exposed to improve the connection reliabilityat the time of packaging the semiconductor device.

[0026] According to still another aspect of the invention, there isprovided a method of manufacturing a resin-sealed type semiconductordevice, comprising the steps of: preparing a lead frame in which aplurality of leads are arranged around a tub for supporting asemiconductor chip; bonding the tub and the semiconductor chip;connecting the surface electrodes of the semiconductor chip and thecorresponding ones of the leads by connecting members; forming a sealingbody by resin-sealing the semiconductor chip and the connecting memberson the lead frame on the semiconductor chip arranging side, to arrangethe plurality of leads on the face of the semiconductor device mountingside with the individual inner portions of the adjoining ones of theleads being separated; exposing the plurality of leads by polishing theface of the sealing body on the semiconductor device mounting side; andcutting and separating the individual leads from the frame portion ofthe lead frame by pressing, after the lead frame is placed on a cuttingdie with the face of the sealing body on the semiconductor devicemounting side being directed upward, the leads under pressure with thecutting blade of the cutting die from the side of the mounted face ofthe leads.

[0027] According to a further aspect of the invention, there is provideda method of manufacturing a resin-sealed type semiconductor device,comprising the steps of: preparing a lead frame which is made of acopper alloy and in which a plurality of leads are arranged around a tubfor supporting a semiconductor chip; bonding the tub and thesemiconductor chip; connecting the surface electrodes of thesemiconductor chip and the corresponding ones of the leads by bondingwires; forming a sealing body by resin-sealing the semiconductor chipand the wires on the lead frame on the semiconductor chip arrangingside, to arrange the plurality of leads on the face of the semiconductordevice mounting side with the individual inner portions of the adjoiningones of the leads being separated; exposing the plurality of leads bypolishing the face of the sealing body on the semiconductor devicemounting side with a brush which is made of a polyamide resin havingabrasive grain thereon; forming a soldered layer on the mounted faces ofthe leads, as exposed from the face on the semiconductor device mountingside; and cutting and separating the individual leads from the frameportion of the lead frame by pressing, after the lead frame is placed ona cutting die with the face of the sealing body on the semiconductordevice mounting side being directed upward, the leads under pressurewith the cutting blade of the cutting die from the side of the mountedface of the leads.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028]FIG. 1 is a perspective view showing one embodiment of thestructure of a semiconductor device (QFN) according to the invention;

[0029]FIG. 2 is a bottom view showing the structure of the QFN shown inFIG. 1;

[0030]FIG. 3 is a sectional view showing the structure of the QFN shownin FIG. 1;

[0031] Of FIGS. 4A to 4C showing one example showing the package statein which the QFN shown in FIG. 1 is mounted on a mount substrate: FIG.4A is a sectional view of a portion; FIG. 4B is an enlarged sectionalview, as taken in a lead longitudinal direction, of a portion of asoldered portion; and FIG. 4C is an enlarged sectional view, as taken ina lead transverse direction, of a portion of the soldered portion;

[0032]FIG. 5 is a flow chart showing a manufacture method of one exampleof an assembling procedure in a method of manufacturing the QFN shown inFIG. 1;

[0033]FIGS. 6A, 6B, 6C, 6D, 6E and 6F are sectional views showing oneexample of the structures of intermediates to be treated at theindividual steps of the manufacture method shown in FIG. 5;

[0034]FIG. 7 is a sectional view showing one example showing the statein which a resin burr is formed on the back face of a sealing body afterthe molding step of the manufacture method of the QFN shown in FIG. 1;

[0035]FIG. 8 is a top plan view showing the structure of a matrix frameor one example of a lead frame to be used for manufacturing the QFNshown in FIG. 1;

[0036]FIG. 9 is a top plan view showing a portion of one example of thestructure of a unit lead frame in the matrix frame shown in FIG. 8;

[0037]FIG. 10 is a sectional view showing a portion of one example of awiring method in the wire bonding step of the manufacture of the QFNshown in FIG. 1;

[0038]FIG. 11 is a sectional view showing a portion of one example of amolded state in the manufacture of the QFN shown in FIG. 1;

[0039] Of FIGS. 12A to 12C showing one example of the state of thematrix frame molded in the manufacture of the QFN shown in FIG. 1: FIG.12A is an enlarged top plan view showing a portion; FIG. 12B is asectional view taken along line A-A of FIG. 12A; and FIG. 12C is asectional view taken along line B-B of FIG. 12A;

[0040]FIG. 13 is a sectional view showing a portion of one example ofthe polished sate in which a sealing body is polished on its back facein the manufacture of the QFN shown in FIG. 1;

[0041]FIG. 14 is a top plan view showing the example of the polishedsate in which the sealing body is polished on its back face in themanufacture of the QFN shown in FIG. 1;

[0042]FIGS. 15A, 15B, 15C and 15D are sectional views showing portionsof one example of a lead cutting procedure in the manufacture of the QFNshown in FIG. 1;

[0043]FIG. 16 is a sectional view showing a flatness correcting methodaccording to an application of the semiconductor device manufacturingmethod of the invention;

[0044]FIG. 17 is a sectional view showing a package thickness adjustingmethod according to an application of the semiconductor devicemanufacturing method of the invention;

[0045]FIG. 18 is a sectional view showing a structure of a semiconductordevice (QFN) according to another embodiment of the invention; and

[0046] Of FIGS. 19A and 19B showing a molding method and a structure ofa semiconductor device (QFN) to be compared with the semiconductordevice of the invention, FIG. 19A is a sectional view showing a portionof a molding state, and FIG. 19B is a sectional view of the QFN to becompared.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] In the following embodiments, the description of identical orsimilar portions will not be repeated on principle, unless otherwiseespecially necessary.

[0048] Moreover, the following embodiments will be described, if neededfor conveniences, by dividing them into a plurality of sections ormodes, which are not independent of one another, unless otherwiseexplicitly specified so, but are partially or wholly in relations ofmodifications, details or supplementary explanations of others.

[0049] In the following embodiments, on the other hand, when referenceis made to the number (including the numbers, numerical values,quantities and ranges) of elements, the invention should not be limitedto the specific number, unless otherwise explicitly specified orapparently limited to that number, but may be more or less the specificnumber.

[0050] The embodiments of the invention will be described in detail withreference to the accompanying drawings. Here, throughout all thedrawings for explaining the embodiments, parts having identicalfunctions will be designated by common reference numerals, and theirrepeated descriptions will be omitted.

[0051]FIG. 1 is a perspective view showing one embodiment of thestructure of a semiconductor device (QFN) according to the invention;FIG. 2 is a bottom view showing the structure of the QFN shown in FIG.1; FIG. 3 is a sectional view showing the structure of the QFN shown inFIG. 1; Of FIGS. 4A to 4C showing one example showing the package statein which the QFN shown in FIG. 1 is mounted on a mount substrate: FIG.4A is a sectional view of a portion; FIG. 4B is an enlarged sectionalview, as taken in a lead longitudinal direction, of a portion of asoldered portion; and FIG. 4C is an enlarged sectional view, as taken ina lead transverse direction, of a portion of the soldered portion; FIG.5 is a flow chart showing a manufacture method of one example of anassembling procedure in a method of manufacturing the QFN shown in FIG.1; FIGS. 6A, 6B, 6C, 6D, 6E and 6F are sectional views showing oneexample of the structures of intermediates to be treated at theindividual steps of the manufacture method shown in FIG. 5; FIG. 7 is asectional view showing one example showing the state in which a resinburr is formed on the back face of a sealing body after the molding stepof the manufacture method of the QFN shown in FIG. 1; FIG. 8 is a topplan view showing the structure of a matrix frame or one example of alead frame to be used for manufacturing the QFN shown in FIG. 1; FIG. 9is a top plan view showing a portion of one example of the structure ofa unit lead frame in the matrix frame shown in FIG. 8; FIG. 10 is asectional view showing a portion of one example of a wiring method inthe wire bonding step of the manufacture of the QFN shown in FIG. 1;FIG. 11 is a sectional view showing a portion of one example of a moldedstate in the manufacture of the QFN shown in FIG. 1; Of FIGS. 12A to 12Cshowing one example of the state of the matrix frame molded in themanufacture of the QFN shown in FIG. 1: FIG. 12A is an enlarged top planview showing a portion; FIG. 12B is a sectional view taken along lineA-A of FIG. 12A; and FIG. 12C is a sectional view taken along line B-Bof FIG. 12A; FIG. 13 is a sectional view showing a portion of oneexample of the polished sate in which a sealing body is polished on itsback face in the manufacture of the QFN shown in FIG. 1; FIG. 14 is atop plan view showing the example of the polished sate in which thesealing body is polished on its back face in the manufacture of the QFNshown in FIG. 1; and FIGS. 15A, 15B, 15C and 15D are sectional viewsshowing portions of one example of a lead cutting procedure in themanufacture of the QFN shown in FIG. 1.

[0052] The semiconductor device of this embodiment, as shown in FIGS. 1to 3, is of a small resin-sealed type and a surface mount type. Thisembodiment will be described by taking up a QFN (Quad Flat NonleadedPackage) 7 as one example of the semiconductor device.

[0053] On the other hand, the QFN 7 is a small-sized semiconductorpackage, as incorporated mainly into a mobile electronic device, and isof a surface mount, in which a plurality of leads 1 a connected with aland 9 a, i.e., substrate side terminals of a mount substrate 9 (asreferred to FIG. 4) such as a printed-circuit board are arranged on theface of the semiconductor device mounting side (as will be called the“back face 3 a”) of a sealing body 3 made of a mold, as shown in FIG. 2.

[0054] Here, a semiconductor chip 2, as shown in FIG. 3, to beincorporated into the QFN 7 is a chip for a microcomputer or an ASIC(Application Specific Integrated Circuit), but should not be limitedthereto.

[0055] Here will be described the construction of the QFN 7(semiconductor device) of this embodiment with reference to FIGS. 1 to4.

[0056] The QFN 7 is constructed to include: a tub le supporting thesemiconductor chip 2 having a semiconductor integrated circuit formed onits principal face 2 b; the sealing body 3 formed by sealing thesemiconductor chip 2 with a resin; the plurality of leads 1 a made of acopper alloy, arranged around the tub 1 e, exposed to the back face 3 aof the sealing body 3, and having a soldered or plated layer 8 formed atthe exposed portion (or a mounted face 1 d); and bonding wires 4 (orconnecting members) connecting pads 2 a or the surface electrodes of thesemiconductor chip 2 with the corresponding leads 1 a. As shown in FIG.4C, two widthwise edge portions 1 c, as exposed from the back face 3 aof the sealing body 3, of the lead 1 a are formed into rounded faces 1g, and the central portion, as including the rounded faces 1 g, of themounted face 1 d of the lead 1 a is protruded from the back face 3 a ofthe sealing body 3.

[0057] Here, the protrusion of the lead 1 a from the back face 3 a ofthe sealing body 3 is achieved at a polishing step S4, as shown in FIG.5, of a manufacture method of the QFN 7 by polishing the back face 3 aof the sealing body 3 with a brush 10 which is made of a polyamide resinhaving abrasive gain adhered thereon, as shown in FIG. 13.

[0058] When the back face 3 a of the sealing body 3 is polished with thebrush 10 having abrasive grain, not only the resin of the back face 3 aof the sealing body 3 but also the longitudinal edge portions 1 c of thelead 1 a are polished, as shown in FIG. 4C, so that the edge portions 1c become the rounded faces 1 g.

[0059] By comparing the thickness (T₁) of the central portion of thelead 1 a in the widthwise section of the lead 1 a with the thickness(T₂) of the end portions of the lead 1 a, therefore, the lead 1 a can beformed to satisfy T₁>T₂. After the polishing step, at a plating step S5shown in FIG. 5, the mounted face 1 d of the lead 1 a is plated withsolder so that the soldered layer 8 shown in FIG. 3 is formed on themounted face 1 d.

[0060] Here, the protrusion (T₁-T₂) at the central portion is about 1 to3 microns.

[0061] In the QFN 7 of this embodiment, on the other hand, the tub 1 ehas a thickness of about one half as large as that of the thickness ofthe lead 1 a, as shown in FIG. 3.

[0062] Thus, at the time of manufacturing a matrix frame 1 (or leadframe) shown in FIG. 8, the back face 1 h (as referred to FIG. 3) of thetub 1 e is etched off so that a mold resin 15 shown in FIG. 11 can bearranged on the side of the back face 1 h of the tub 1 e, too, withoutelevating the position of the tub 1 e with respect to the sealing body3.

[0063] Since the vertical position of the tub 1 e is unchanged in theQFN 7 shown in FIG. 3, therefore, the QFN 7 can be thinned, and the tub1 e is completely buried in the sealing body 3 so that the substrate canalso be wired at positions on the lower side of the sealing body 3 inthe mount substrate 9 when the QFN 7 is mounted on the mount substrate9, as shown in the packaged mode of FIG. 4A. Here on the surface of themount substrate 9, there is formed a solder resist 9 b or an insulatingfilm for covering the substrate wires.

[0064] In the QFN 7, on the other hand, the semiconductor chip 2 issupported by the tub 1 e, which is exemplified in this embodiment by anX-shaped small cross tub, as shown in FIG. 9. In other words, the tub 1e is made far smaller in size than the semiconductor chip 2.

[0065] As a result, the semiconductor chips 2 of a plurality of kinds ofsizes can be packaged on the tub 1 e of one kind, and the contact areaof the semiconductor chip 2 with the mold resin 15 on the side of itsback side 2 c can be enlarged to improve the contact between thesemiconductor chip 2 and the sealing body 3 thereby to prevent thesealing body 3 and the semiconductor chip 2 from being separated.

[0066] In the QFN 7 of this embodiment, on the other hand, a lead burr 1i shown in FIG. 4B, as formed on the lead 1 a at the step S6 of cuttingthe lead 1 a, as shown in FIG. 5, is formed at the end portion on theupper side of the lead 1 a, i.e., on the face of the lead 1 a, asopposed to the mounted face 1 d.

[0067] When the lead 1 a is cut off the matrix frame 1 at the cuttingstep by the cutting punch 12 a (or cutting blade) of a cutting die 12shown in FIG. 15, it is pressed and cut with a shearing force by thecutting punch 12 a from the side of its mounted face 1 d of the lead 1a. As a result, the lead burr 1 i is formed at the upper side endportion of the lead 1 a.

[0068] On the other hand, the semiconductor chip 2 is given a thicknessof about 0.2 to 0.3 mm, for example, and is fixed on the tub 1 e with adie bond material 5 such as an epoxy adhesive.

[0069] On the other hand, the lead frame having the tub 1 e and the lead1 a, i.e., the matrix frame 1 is made of a copper (Cu) alloy, an alloy(Fe—Ni) of iron and nickel or the like but is preferably made of thecopper alloy.

[0070] Moreover, the matrix frame 1 has a thickness of about 0.09 to0.21 mm, for example. Therefore, the tub 1 e or the lead 1 a has asimilar thickness such as about one half as large as that of the lead 1a when the tub 1 e is half-etched as in the QFN 7 of this embodiment.

[0071] Here, the matrix frame 1 should not be limited to theabove-specified materials and thicknesses.

[0072] On the other hand, the bonding wire 4 (or the connecting member)for connecting the pad 2 a of the semiconductor chip 2 with thecorresponding lead 1 a is made of a gold wire, for example.

[0073] Moreover, the sealing body 3 is formed by sealing it with a resinaccording to the molding method, and the used sealing mold resin 15shown in FIG. 11 is a thermoset epoxy resin, for example.

[0074] Here, the sealing body 3 made of the mold resin 15 has athickness of about 0.5 to 0.95 mm, for example.

[0075] On the other hand, the plated layer to be formed on the mountedface id of each lead 1 a is the soldered layer 8 (Sn—Pb), for example,in this embodiment but may be another Sn solder such as a solder ofSn—Ag—Bi, a solder of Sn—Ag—Cu or a palladium (Pd) solder.

[0076] The plating thickness is 0.05 mm or less, for example, and ispreferably about 0.01 mm.

[0077] Here, this plating thickness is the stand-off extent (orstand-off height) in the QFN 7.

[0078] Where the thickness of the sealing body 3 is about 0.5 to 0.95 mmand where the thickness of the soldered layer 8 is about 0.01 mm, forexample, the height of the mount substrate 9 from the land 9 a when theQFN 7 is packaged can be suppressed to 1.0 mm or less.

[0079] According to the QFN 7 of this embodiment, by polishing the backface 3 a of the sealing body 3 after the sealing body was formed by theresin mold, a resin burr 16 (of the leakage resin), as formed on theback face 3 a of the sealing body 3 and shown in FIG. 6C, and the resinburr 16 (or the resin flash), as shown in FIG. 7, can be removed toexpose the mounted face 1 d of each lead 1 a sufficiently. This makes itpossible to expose the connection region of the lead 1 a, as needed whenthe QFN 7 is mounted on the mount substrate 9, without fail.

[0080] In short, it is possible to retain the connection region of thelead 1 a, as needed at the time of packaging the QFN 7.

[0081] As a result, the solder wettability can be improved to improvethe connection reliability at the time when the QFN 7 is mounted on themount substrate 9 or the like.

[0082] On the other hand, the flatness of the back face 3 a of thesealing body 3 can be improved by polishing it thereby to improve thepackageability of the QFN 7.

[0083] In the back face 3 a of the sealing body 3, moreover, the roundedfaces 1 gare formed at the longitudinal edge portions 1 c of the lead 1a, as shown in FIG. 4C, so that the thickness (T₁) of the centralportion of the lead 1 a in the widthwise section of the lead 1 a can bemade larger than the thickness (T₂) of the end portions of the lead 1 a(T₁>T₂).

[0084] As a result, the stand-off extent at the time of packaging theQFN 7 can be retained.

[0085] Since the widthwise central portion of the lead 1 a is thickerthan the end portions, more specifically, a solder paste 14 can runsufficiently to the rounded faces 1 g at the widthwise end portions ofthe lead 1 a, as shown in FIG. 4C, when the mount substrate 9 issoldered.

[0086] Therefore, solder fillets in the solder connection can besufficiently formed to improve the connection reliability at the time ofmounting the QFN 7 on the mount substrate 9.

[0087] In the QFN 7 of this embodiment, on the other hand, the lead burr1 i is formed on the upper side of the lead 1 a, as shown in FIG. 4B.

[0088] As a result, the mounted face id of the lead 1 a of the QFN 7does not have lead burr 1 i formed but is flat so that thepackageability at the time when the QFN 7 is mounted on the mountsubstrate 9 and the connection reliability at the soldering time can beimproved.

[0089] Since the matrix frame 1 is made of the copper alloy, on theother hand, its material cost can be lowered, and the heat radiation ofthe QFN 7 can be improved.

[0090] Therefore, it is possible to improve the reliability of the QFN7.

[0091] On the other hand, the soldered layer 8 is formed as a platedlayer on the mounted face 1 d of the lead 1 a of the QFN 7 so that thesolder connectability at the time of mounting the QFN 7 on the mountsubstrate 9 can be improved.

[0092] Where the palladium plated layer is formed as the plated layer,the QFN 7 can be set free of lead when it is manufactured.

[0093] Next, the method of manufacturing the QFN 7 of this embodimentwill be described with reference to the flow chart of the manufacturemethod shown in FIG. 5.

[0094] First of all, there is prepared the matrix frame 1 (or the leadframe), as shown in FIG. 8, which is made of the copper alloy with theplurality of leads 1 a being arranged around the tub 1 e capable ofsupporting the semiconductor chip 2.

[0095] Here in this matrix frame 1, unit lead frames 1 j for theindividual package regions are formed in a plurality of rows and aplurality of columns so that a number of QFNs 7 can be manufactured fromone matrix frame 1. FIG. 9 shows the structure of the unit lead frame 1j of the matrix frame 1 of FIG. 8 in detail.

[0096] In the matrix frame 1 of this embodiment, on the other hand, ofthe plurality of leads 1 a, the individual inner portions 1 b of theadjoining leads 1 a are separated in advance. After the resin moldingstep, the lead root end portions, as slightly protruding from thesealing body 3, are connected and supported by a frame portion if.

[0097] Here in the matrix frame 1, as shown in FIG. 8, a plurality ofguide holes 1 k are formed on the two side portions for providing guidesat the transferring time and at the positioning time.

[0098] As shown in FIG. 9, moreover, at each unit lead frame 1 j, thetub 1 e is supported in four directions by tub suspending leads 11, andslits 1 m are formed around the individual leads 1 a for absorbing thestress.

[0099] After this, there is prepared the semiconductor chip 2 having thesemiconductor integrated circuit formed on the principal face 2 b. Thesemiconductor chip 2 is subjected to the die bonding (or chip mountingor pellet bonding) treatment at step S1.

[0100] Specifically, the tub 1 e in each unit lead frame 1 j of thematrix frame 1 and the semiconductor chip 2 are bonded.

[0101] At this time, the die bonding material 5 such as silver paste isapplied to the tub 1 e, as shown in FIG. 6A, to bond the tub 1 e and theback face 2 c of the semiconductor chip 2 through that die bondingmaterial 5.

[0102] In other words, the semiconductor chip 2 is fixed over the tub 1e through the die bonding material 5 with its principal face 2 bdirected upward.

[0103] After this, there is performed a wire bonding treatment, asindicated at step S2.

[0104] First of all, the matrix frame 1 is set on a heat stage 17, asshown in FIG. 10, and the pads 2 a of the semiconductor chip 2 and theinner portions 1 b of the corresponding leads 1 a are connected by thewires 4 of the gold line, as shown in FIG. 6B, by using a capillary 6 ora bonding tool.

[0105] At this time, in this embodiment, the pads 2 a of thesemiconductor chip 2 and the wires 4 are connected at first on the firstbond side, and the wires 4 and the inner portions 1 b of the leads 1 aare then connected on the second bond side.

[0106] After this, a molding treatment is performed, as indicated atstep S3. Here, the molding treatment is done by the transfer moldingmethod.

[0107] At first, the wire-bonded matrix frame 1 (as referred to FIG. 10)is set on the upper part 11 a of a mold die 11, as shown in FIG. 11, andis clamped by the upper part 11 a and a lower part 11 b. After this, themold resin 15 is injected into a cavity 11 c which is defined by theupper part 11 a and the lower part 11 b.

[0108] Here in the matrix frame 1 used in this embodiment, theindividual inner portions 1 b of the adjoining ones of the plurality ofleads 1 a are separated in advance. By resin-molding the semiconductorchip 2 and the wires 4 on the arranged side (although the back face 1 hof the tub 1 e is included) of the semiconductor chip 2 on the matrixframe 1, therefore, the plurality of leads 1 a are arranged on the backface 3 a to form the sealing body 3 with the individual inner portions 1b of the adjoining leads 1 a being separate.

[0109] Therefore, the mold of this embodiment is the one-side mold whichuses the upper part 11 a having no recessed cavity 11 c formed.

[0110] The mold resin 15 is set, when charged up, after lapse of apredetermined time period, and the mold is then opened to extract thematrix frame 1 from the mold die 11.

[0111] Here, FIGS. 12A, 12B and 12C show the states of the matrix frame1 after molded. In the matrix frame 1 extracted from the mold die 11, asshown in FIGS. 12A and 12C, a residual resin such as a gate 18 or arunner 19 is formed together with the plurality of sealing bodys 3.

[0112] Here in the molded matrix frame 1, on the back face 3 a of eachsealing body 3, there are formed the resin burr 16 of the leakage resin,as shown in FIG. 6C, and the resin burr 16 of the resin flash, as shownin FIG. 7. At this stage, the connection region for the mounted faces idof the leads 1 a is not sufficiently retained on the back face 3 a ofthe sealing body 3.

[0113] After this, the polishing treatment is performed, as indicated atstep S4. Specifically, the back face 3 a of each sealing body 3 in thematrix frame 1 is polished to expose the mounted face 1 d of each lead 1a sufficiently for retaining the connection region of the mounted face 1d sufficiently.

[0114] At this time, in this embodiment, the back side 3 a of thesealing body 3 is polished with the brush 10, as made of the polyamideresin having the abrasive grain and as shown in FIG. 13, to expose theplurality of leads 1 a to the outside.

[0115] Here, the brush 10 is made of the resin having the abrasive grainthereon and is preferably made of a polyamide resin. However, the brush10 may be made of a nonwoven fabric and is borne turnably and slidably.

[0116] For this polishing treatment, the molded matrix frame 1 is set ona mask jig 21 which is attached to a polishing stage 20.

[0117] Here, the mask jig 21 is provided in a matrix arrangement with aplurality of through holes 21 a according to the positions and sizes ofthe plurality of sealing bodys 3 of the matrix frame 1.

[0118] When the matrix frame 1 is set on the polishing stage 20,therefore, its face on the side having the sealing bodys 3 is directeddownward, as shown in FIG. 13, so that the individual sealing bodys 3are arranged in the individual through holes 21 a of the mask jig 21placed on the polishing stage 20.

[0119] As a result, the sealing bodys 3 have their back faces 3 adirected upward on the polishing stage 20.

[0120] After this, an evacuation is made from the side of the back face21 b of the mask jig 21 to fix the matrix frame 1 on the mask jig 21.

[0121] Subsequently, the polishing treatment is performed by turning thebrush 10 at a predetermined speed while discharging cooling water 23from nozzles 22 to the back faces 3 a of the individual sealing bodys 3and simultaneously by moving the brush 10 in a predetermined direction.

[0122] Here in the moving locus of the brush 10, for example, the brush10 is preferably moved so uniformly over the matrix frame 1 as to comeinto substantially homogeneous contact with the individual sealing bodys3 of the matrix frame 1. In this embodiment, as shown in FIG. 14, thebrush 10 is reciprocated, as indicated at 24, in parallel with thelongitudinal direction of the matrix frame 1. However, the moving locusof the brush 10 should not be limited to that shown in FIG. 14 but maybe any if it is homogeneous over the matrix frame 1.

[0123] During the movement, moreover, the brush 10 continuously appliesa predetermined load to the back faces 3 a of the individual sealingbodys 3 thereby to polish the back faces 3 a.

[0124] Here, the abrasion of the back faces 3 a of the sealing bodys 3is about 1 to 3 microns, for example.

[0125] As a result, the resin burr 16, as shown in FIG. 6C or 7, can beremoved to expose the mounted face id of each lead 1 a so sufficientlyon the back face 3 a of the sealing body 3 as to retain the connectionregion, as shown in FIG. 6D.

[0126] By polishing with the brush 10 made of the polyamide resin havingthe abrasive grain, moreover, the mounted face 1 d of the lead 1 a canbe so shaped that the longitudinal edge portions 1 c of the lead 1 a maybe the rounded faces 1 g, as shown in FIG. 4C. As a result, thethickness (T1) of the central portion of the lead 1 a in the widthwisesection of the lead 1 a can be made larger than that (T₂) of the endportions of the lead 1 a (T₁>T₂).

[0127] After this, there is performed the plating treatment, asindicated at step S5.

[0128] Specifically, the mounted face id of each lead 1 a, as exposedfrom the back face 3 a of the sealing body 3, is plated with thesoldered layer 8 (or the plated layer), as shown in FIG. 6E.

[0129] At this time, the soldered layer 8 is formed by the electrolyticmethod, for example, to have a thickness of about 0.05 mm (at themaximum).

[0130] After this, there is performed the cutting treatment, asindicated at step S6.

[0131] At the cutting step, as shown in FIG. 15A, the matrix frame 1 isplaced on a lead cutting die 12 b of the cutting die 12 with the backface 3 a of the sealing body 3 being directed upward. Subsequently, thematrix frame 1 is clamped by the lead cutting die 12 b and a stripper 12c.

[0132] After this, as shown in FIG. 15B, the lead 1 a is pressed (orgiven a shearing force) downward or from the side of the mounted face 1d by the cutting punch 12 a (or cutting blade) of the cutting die 12 sothat it is cut off the frame portion if, as shown in FIG. 9, of thematrix frame 1 so that the individual leads 1 a are separated from theframe portion 1 f.

[0133] Here, by pressing the cutting punch 12 a downward of the lead 1a, foreign substances such as cut chips 13 are enabled to fall down, asshown in FIG. 15C, and the lead burr 1 i can be formed on the face ofthe lead 1 a on the side opposed to the mounted face id, as shown inFIG. 15D and FIG. 4B.

[0134] Thus, there can be assembled the QFN 7, as shown in FIGS. 1 to 3and FIG. 6F.

[0135] On the other hand, the packaged state of the completed QFN 7 onthe mount substrate 9 is shown in FIG. 4.

[0136] According to the manufacture method of the QFN 7 (or thesemiconductor device) of this embodiment, the resin burr 16, as formedon the back face 3 a of the sealing body 3, can be removed by polishingthe back face 3 a of the sealing body 3 after the resin molding step sothat the mounted face 1 d of the lead 1 a can be reliably exposed.

[0137] As a result, the connection region (or the plated region) on themounted face 1 d of the lead 1 a at the time of packaging the QFN 7 canbe retained to improve the connection reliability of the QFN 7.

[0138] Since the mounted face 1 d of the lead 1 a can be reliablyexposed to the back face 3 a by polishing the back face 3 a of thesealing body 3 after the resin molding step, on the other hand, it ispossible to manufacture even the QFN 7 of the large size (having 100pins or more), although having been relatively difficult to manufacture.

[0139] By polishing the back face 3 a of the sealing body 3 after theresin molding step, moreover, the resin burr 16 can be removed from theback face 3 a. This makes it unnecessary to manage the pressure of themold die 11, as might otherwise be caused by the resin burr 16 such asthe resin flash, so that the method management in the molding step canbe facilitated.

[0140] Since the resin burr 16 is removed from the back face 3 a of thesealing body 3, on the other hand, the frequency to clean the mold die11 can be reduced to improve the throughput of the molding step.

[0141] After the resin molding step, on the other hand, the mounted face1 d of the lead 1 a can be reliably exposed to the back face 3 a of thesealing body 3 by polishing the back face 3 a so that the laminatemolding method is not needed. This makes it unnecessary to modify themolding apparatus so that no cost is included for the modification.

[0142] Without the laminate molding method, moreover, the clamp is notmade defective, as might otherwise occur at the lead clamping time forcutting the lead, so that the lead can be prevented from becomingdefective.

[0143] Since the back face 3 a of the sealing body 3 is polished byusing the brush 10 made of the polyamide resin, on the other hand, thepolishing treatment can be performed at an abrasion rate of aboutseveral microns according to the warpage (or deformation), if any, ofthe back face 3 a of the sealing body 3.

[0144] As a result, the lead 1 a can be exposed by polishing the backface 3 a of the sealing body 3 while keeping the shape of its back face3 a.

[0145] Since the back face 3 a of the sealing body 3 is polished byusing the brush 10 made of the polyamide resin, on the other hand, thelongitudinal edge portions 1 c of the lead 1 a on the back face 3 a ofthe sealing body 3 can be formed into the rounded faces 1 g, and thethickness (T₁) of the central portion of the lead 1 a can be made largerthan that (T₂) of the end portions of the lead 1 a (T₁>T₂).

[0146] As a result, the widthwise thickness of the central portion ofthe lead 1 a is made larger than that of the end portions so that thesolder paste 14 can run sufficiently to the rounded faces 1 g at thewidthwise end portions of the lead 1 a, as shown in FIG. 4C, when themount substrate 9 is soldered. As a result, the solder fillet at thesoldered connection can be sufficiently formed to enhance the connectionreliability at the time when the QFN 7 is mounted on the mount substrate9 or the like.

[0147] At the cutting step of the lead 1 a, on the other hand, theforeign substances such as the cut chips 13 can be dropped down bybringing the cutting punch 12 a downward (from the side of the mountedface id) under the pressure into contact with the lead 1 a.

[0148] As a result, the foreign substances such as the cut chips 13 canbe efficiently collected to improve the working efficiency of thecutting step.

[0149] By bringing the cutting punch 12 a downward (from the side of themounted face id) under the pressure into contact with the lead 1 a, onthe other hand, the foreign substances go around to the face opposed tothe mounted face id of the lead 1 a so that the mounted face 1 d can beset free of the foreign substances.

[0150] Thus, it is possible to improve the connection reliability at thetime of packaging the QFN 7.

[0151] By bringing the cutting punch 12 a downward (from the side of themounted face id) under the pressure into contact with the lead 1 a,moreover, the lead burr 1 i can be formed on the faces, as opposed tothe mounted face id, of the lead 1 a.

[0152] As a result, the mounted face id of the lead 1 a can be flattedwithout any burr to improve the connection reliably at the time ofpackaging the QFN 7 like before.

[0153] Although our invention has been specifically described inconnection with its embodiments, it should not be limited to thoseembodiments but could naturally be modified in various manners withoutdeparting from the gist thereof.

[0154] In connection with the embodiments, for example, there has beendescribed the technique for removing the resin burr 16 such as theleakage resin or the resin flash, as formed on the back face 3 a of theresin-molded sealing body 3, by polishing the back face 3 a. An effectother than that for removing the resin burr 16 (as referred to FIG. 6C)could be obtained, as exemplified in other embodiments shown in FIGS. 16and 17.

[0155] In the embodiment of FIG. 16, more specifically, the flatness ofthe back face 3 a of the resin-molded sealing body 3 is adjusted bypolishing the back face 3 a. As a result, the back face 3 a can becleared of the resin burr 16 and can be easily given a desired flatness.

[0156] In FIG. 17, moreover, the resin-molded sealing body 3 is thinnedby polishing its back face 3 a. As a result, the back face 3 a can becleared of the resin burr 16, and the QFN 7 (as referred to FIG. 1) canbe made thinner.

[0157] By the semiconductor device manufacturing method according to theforegoing and other embodiments, therefore, it is possible to deburr theback face 3 a of the QFN 7, to flatten the back face 3 a and to thin theQFN 7.

[0158] On the other hand, the foregoing embodiment has been described onthe case in which the QFN 7 has the tub-buried structure. In anotherembodiment shown in FIG. 18, however, the QFN 7 may be modified into thetub-exposed structure in which the tub 1 e is exposed to the back side 3a of the sealing body 3.

[0159] In this case, the back face 3 a of the sealing body 3 is polishedafter molded with the resin, to expose the individual leads 1 a and thetub 1 e to the back face 3 a of the sealing body 3. In the QFN 7 havingthe tub-exposed structure shown in FIG. 18, too, there can be attainedan effect similar to that of the QFN 7 of the tub-buried structure, ashas been described in connection with the foregoing embodiment.

[0160] Moreover, the foregoing embodiment has been described on the casein which the tub 1 e is the X-shaped small cross tub. However, the shapeof the tub 1 e should not be especially limited but may be rectangularor circular.

[0161] Moreover, the tub 1 e should not be limited to the small tub butmay be of the type larger than the semiconductor chip 2.

[0162] On the other hand, the foregoing embodiment has been described onthe case in which the lead frame is the matrix frame 1. However, thelead frame may be a series of unit lead frames lj arranged in a row.

[0163] Moreover, the foregoing embodiment has been described on the casein which the back face 3 a of the sealing body 3 is polished with thebrush 10. However, the method of deburring the back face 3 a of the QFN7, flattening the back face 3 a and thinning the QFN 7 may employ agrinding stop other than the brush 10.

[0164] On the other hand, the foregoing embodiment has been described onthe case in which the lead 1 a is press-cut by bringing the cuttingblade (or the cutting punch 12 a) under pressure from the side of themounted face id of the lead 1 a into contact. However, the cutting neednot be performed from the side of the mounted face 1 d but may beeffected from the opposite side.

[0165] In the method of manufacturing the semiconductor device of theinvention, moreover, the technique of polishing the back side of thesealing body 3 and the technique of cutting the lead 1 a, as have beendescribed in connection with the foregoing embodiment, may be performedboth simultaneously or either solely.

[0166] Here, the foregoing embodiment has been described on the case inwhich the semiconductor device is the small-sized QFN 7. However, thesemiconductor device may be any other than the QFN 7 if it is of theresin-sealed type and of the surface mount type in which it is assembledby using the lead frame.

[0167] The effects to be obtained by the representative inventiondisclosed herein will be briefly described in the following.

[0168] (1) By polishing the back face of the resin-molded sealing body,it is possible to remove the resin burr which is formed on the back faceof the sealing body. As a result, the mounted face of the lead can bereliably exposed. Therefore, the connection region (or the platedregion) can be retained on the mounted face of the lead at the time ofpackaging the semiconductor device. As a result, it is possible toimprove the connection reliability of the semiconductor device.

[0169] (2) By polishing the back face of the resin-molded sealing body,it is possible to remove the resin burr which is formed on the back faceof the sealing body. Therefore, the pressure management of the mold die,as might otherwise be caused by the resin burr such as the resin flashburr, can be eliminated to make it easy to manage the molding step.

[0170] (3) Since the mounted face of the lead can be reliably exposed bypolishing the back face of the resin-molded sealing body, no laminatemolding method is needed to require no modification of the moldingapparatus so that no cost is involved for the modification. No laminatemolding method is performed to cause no defect at the time of clampingthe lead when the lead is cut, so that the lead cutting defect can beprevented.

[0171] (4) By polishing the back face of the sealing body with the brushmade of the polyamide resin, the back face of the sealing body can bepolished, even if deformed or warped, at the abrasion rate of aboutseveral microns according to the warpage of that back face.

[0172] (5) By polishing the back face of the sealing body with the brushmade of the polyamide resin, the longitudinal edge portions of the leadon the back face of the sealing body can be formed into the roundedfaces. Therefore, the widthwise central portion of the lead can be madethicker than the end portions so that the solder paste can runsufficiently to the rounded faces of the widthwise end portions of thelead when the mount substrate or the like is soldered. Therefore, thesolder fillet in the solder connection can be sufficiently formed toenhance the connection reliability at the time of packaging thesemiconductor device.

[0173] (6) At the cutting step of the lead, the foreign substances suchas the cut chips can be dropped down by bringing the cutting bladedownward under the pressure into contact with the lead. As a result, theforeign substances can be efficiently collected to improve the workingefficiency of the cutting step.

[0174] (7) By bringing the cutting blade downward under the pressureinto contact with the lead, the foreign substances go around to the faceopposed to the mounted face of the lead so that the mounted face can beset free of the foreign substances. Therefore, it is possible to improvethe connection reliability at the time of packaging the semiconductordevice. Moreover, the lead burr can be formed on the upper side of thelead thereby to improve the connection reliability at the time ofpackaging the semiconductor device.

What is claimed is:
 1. A resin-sealed type semiconductor devicecomprising: a tub for supporting a semiconductor chip; a sealing bodyformed by sealing said semiconductor chip with a resin; a plurality ofleads arranged around said tub and exposed to the face of said sealingbody on the semiconductor device mounting side; and connecting membersfor connecting the surface electrodes of said semiconductor chip and thecorresponding ones of said leads, wherein the two widthwise edgeportions of each of said leads are formed of rounded faces, and whereinthe mounted face of said lead including said rounded faces is protrudedat its central portion from the face of said sealing body on saidsemiconductor device mounting side.
 2. A resin-sealed type semiconductordevice comprising: a tub for supporting a semiconductor chip; a sealingbody formed by sealing said semiconductor chip with a resin; a pluralityof leads made of a copper alloy, arranged around said tub, exposed tothe face of said sealing body on the semiconductor device mounting side,and having a plated layer on the portion which is exposed from the faceon said semiconductor device mounting side; and connecting members forconnecting the surface electrodes of said semiconductor chip and thecorresponding ones of said leads, wherein the two widthwise edgeportions of each of said leads are formed of rounded faces, and whereinthe mounted face of said lead including said rounded faces is protrudedat its central portion from the face of said sealing body on saidsemiconductor device mounting side.
 3. A method of manufacturing aresin-sealed type semiconductor device, comprising the steps of:preparing a lead frame in which a plurality of leads are arranged arounda tub for supporting a semiconductor chip; bonding said tub and saidsemiconductor chip; connecting the surface electrodes of saidsemiconductor chip and the corresponding ones of said leads byconnecting members; forming a sealing body by resin-molding saidsemiconductor chip and said connecting members on said lead frame on thesemiconductor chip arranging side, to arrange said plurality of leads onthe face of the semiconductor device mounting side; exposing saidplurality of leads by polishing the face of said sealing body on saidsemiconductor device mounting side; and separating said plurality ofleads from the frame portion of said lead frame.
 4. A method ofmanufacturing a resin-sealed type semiconductor device, comprising thesteps of: preparing a lead frame in which a plurality of leads arearranged around a tub for supporting a semiconductor chip; bonding saidtub and said semiconductor chip; connecting the surface electrodes ofsaid semiconductor chip and the corresponding ones of said leads byconnecting members; forming a sealing body by resin-molding saidsemiconductor chip and said connecting members on said lead frame on thesemiconductor chip arranging side, to arrange said plurality of leadsand said tub on the face of the semiconductor device mounting side withthe individual inner portions of the adjoining ones of said leads beingseparated; exposing said plurality of leads and said tub by polishingthe face of said sealing body on said semiconductor device mountingside; and separating said plurality of leads from the frame portion ofsaid lead frame.
 5. A semiconductor device manufacturing methodaccording to claim 3, wherein said lead frame is made of a copper alloy,and wherein a plated layer is formed on the mounted faces of said leadsafter the resin-molding step.
 6. A method of manufacturing aresin-sealed type semiconductor device, comprising the steps of:preparing a lead frame in which a plurality of leads are arranged arounda tub for supporting a semiconductor chip; bonding said tub and saidsemiconductor chip; connecting the surface electrodes of saidsemiconductor chip and the corresponding ones of said leads byconnecting members; forming a sealing body by resin-molding saidsemiconductor chip and said connecting members on said lead frame on thesemiconductor chip arranging side, to arrange said plurality of leads onthe face of the semiconductor device mounting side with the individualinner portions of the adjoining ones of said leads being separated;exposing said plurality of leads by polishing the face of said sealingbody on said semiconductor device mounting side; and cutting andseparating said individual leads from the frame portion of said leadframe by pressing, after said lead frame is placed on a cutting die withthe face of said sealing body on said semiconductor device mounting sidebeing directed upward, said leads under pressure with the cutting bladeof said cutting die from the side of the mounted face of the leads.
 7. Amethod of manufacturing a resin-sealed type semiconductor device,comprising the steps of: preparing a lead frame which is made of acopper alloy and in which a plurality of leads are arranged around a tubfor supporting a semiconductor chip; bonding said tub and saidsemiconductor chip; connecting the surface electrodes of saidsemiconductor chip and the corresponding ones of said leads byconnecting members; forming a sealing body by resin-molding saidsemiconductor chip and said connecting members on said lead frame on thesemiconductor chip arranging side, to arrange said plurality of leads onthe face of the semiconductor device mounting side with the individualinner portions of the adjoining ones of said leads being separated;exposing said plurality of leads by polishing the face of said sealingbody on said semiconductor device mounting side; forming a plated layeron the mounted faces of said leads, as exposed from the face on saidsemiconductor device mounting side; and cutting and separating saidindividual leads from the frame portion of said lead frame by pressing,after said lead frame is placed on a cutting die with the face of saidsealing body on said semiconductor device mounting side being directedupward, said leads under pressure with the cutting blade of said cuttingdie from the side of the mounted face of the leads.
 8. A semiconductordevice manufacturing method according to claim 3, wherein the face ofsaid sealing body on said semiconductor device mounting side is polishedwith a brush which is made of a polyamide resin having abrasive grainthereon.
 9. A method of manufacturing a resin-sealed type semiconductordevice, comprising the steps of: preparing a lead frame in which aplurality of leads are arranged around a tub for supporting asemiconductor chip; bonding said tub and said semiconductor chip;connecting the surface electrodes of said semiconductor chip and thecorresponding ones of said leads by connecting members; forming asealing body by resin-molding said semiconductor chip and saidconnecting members on said lead frame on the semiconductor chiparranging side, to arrange said plurality of leads on the face of thesemiconductor device mounting side with the individual inner portions ofthe adjoining ones of said leads being separated; exposing saidplurality of leads by polishing the face of said sealing body on saidsemiconductor device mounting side with a brush which is made of apolyamide resin having abrasive grain thereon; and cutting andseparating said individual leads from the frame portion of said leadframe by pressing, after said lead frame is placed on a cutting die withthe face of said sealing body on said semiconductor device mounting sidebeing directed upward, said leads under pressure with the cutting bladeof said cutting die from the side of the mounted face of the leads. 10.A method of manufacturing a resin-sealed type semiconductor device,comprising the steps of: preparing a lead frame which is made of acopper alloy and in which a plurality of leads are arranged around a tubfor supporting a semiconductor chip; bonding said tub and saidsemiconductor chip; connecting the surface electrodes of saidsemiconductor chip and the corresponding ones of said leads byconnecting members; forming a sealing body by resin-molding saidsemiconductor chip and said connecting members on said lead frame on thesemiconductor chip arranging side, to arrange said plurality of leads onthe face of the semiconductor device mounting side with the individualinner portions of the adjoining ones of said leads being separated;exposing said plurality of leads by polishing the face of said sealingbody on said semiconductor device mounting side with a brush which ismade of a polyamide resin having abrasive grain thereon; forming aplated layer on the mounted faces of said leads, as exposed from theface on said semiconductor device mounting side; and separating saidplurality of leads from the frame portion of said lead frame.
 11. Amethod of manufacturing a resin-sealed type semiconductor device,comprising the steps of: preparing a lead frame which is made of acopper alloy and in which a plurality of leads are arranged around a tubfor supporting a semiconductor chip; bonding said tub and saidsemiconductor chip; connecting the surface electrodes of saidsemiconductor chip and the corresponding ones of said leads byconnecting members; forming a sealing body by resin-molding saidsemiconductor chip and said wires on said lead frame on thesemiconductor chip arranging side, to arrange said plurality of leads onthe face of the semiconductor device mounting side with the individualinner portions of the adjoining ones of said leads being separated;exposing said plurality of leads by polishing the face of said sealingbody on said semiconductor device mounting side with a brush which ismade of a polyamide resin having abrasive grain thereon; forming aplated layer on the mounted faces of said leads, as exposed from theface on said semiconductor device mounting side; and cutting andseparating said individual leads from the frame portion of said leadframe by pressing, after said lead frame is placed on a cutting die withthe face of said sealing body on said semiconductor device mounting sidebeing directed upward, said leads under pressure with the cutting bladeof said cutting die from the side of the mounted face of the leads. 12.A method of manufacturing a resin-sealed type semiconductor device,comprising the steps of: preparing a lead frame which is made of acopper alloy and in which a plurality of leads are arranged around a tubfor supporting a semiconductor chip; bonding said tub and saidsemiconductor chip; connecting the surface electrodes of saidsemiconductor chip and the corresponding ones of said leads by bondingwires; forming a sealing body by resin-molding said semiconductor chipand said connecting members on said lead frame on the semiconductor chiparranging side, to arrange said plurality of leads on the face of thesemiconductor device mounting side with the individual inner portions ofthe adjoining ones of said leads being separated; exposing saidplurality of leads by polishing the face of said sealing body on saidsemiconductor device mounting side with a brush which is made of apolyamide resin having abrasive grain thereon; forming a soldered layeron the mounted faces of said leads, as exposed from the face on saidsemiconductor device mounting side; and cutting and separating saidindividual leads from the frame portion of said lead frame by pressing,after said lead frame is placed on a cutting die with the face of saidsealing body on said semiconductor device mounting side being directedupward, said leads under pressure with the cutting blade of said cuttingdie from the side of the mounted face of the leads.
 13. A method ofmanufacturing a resin-sealed type semiconductor device, comprising thesteps of: preparing a lead frame in which a plurality of leads arearranged around a tub for supporting a semiconductor chip; bonding saidtub and said semiconductor chip; connecting the surface electrodes ofsaid semiconductor chip and the corresponding ones of said leads byconnecting members; forming a sealing body by resin-molding saidsemiconductor chip and said connecting members on said lead frame on thesemiconductor chip arranging side, to arrange said plurality of leads onthe face of the semiconductor device mounting side with the individualinner portions of the adjoining ones of said leads being separated;exposing said plurality of leads by polishing the face of said sealingbody on said semiconductor device mounting side at an abrasion rateaccording to a warpage of said face with a brush which is made of apolyamide resin having abrasive grain thereon; and separating saidplurality of leads from the frame portion of said lead frame.
 14. Amethod of manufacturing a resin-sealed type semiconductor device,comprising the steps of: preparing a lead frame in which a plurality ofleads are arranged around a tub for supporting a semiconductor chip;bonding said tub and said semiconductor chip; connecting the surfaceelectrodes of said semiconductor chip and the corresponding ones of saidleads by connecting members; forming a sealing body by resin-moldingsaid semiconductor chip and said connecting members on said lead frameon the semiconductor chip arranging side, to arrange said plurality ofleads on the face of the semiconductor device mounting side with theindividual inner portions of the adjoining ones of said leads beingseparated; forming the two widthwise edge portions of each of said leadsinto rounded faces and protruding the central portion of the mountedface, as including said rounded faces, of said lead from the face ofsaid sealing body on said semiconductor device mounting side bypolishing the face of said sealing body on said semiconductor devicemounting side with a brush which is made of a polyamide resin havingabrasive grain thereon; and separating said plurality of leads from theframe portion of said lead frame.
 15. A method of manufacturing aresin-sealed type semiconductor device, comprising the steps of:preparing a lead frame in which a plurality of leads are arranged arounda tub for supporting a semiconductor chip; bonding said tub and saidsemiconductor chip; connecting the surface electrodes of saidsemiconductor chip and the corresponding ones of said leads byconnecting members; forming a sealing body by resin-molding saidsemiconductor chip and said connecting members on said lead frame on thesemiconductor chip arranging side, to arrange said plurality of leads onthe face of the semiconductor device mounting side; cutting andseparating said individual leads from the frame portion of said leadframe by pressing, after said lead frame is placed on a cutting die withthe face of said sealing body on said semiconductor device mounting sidebeing directed upward, said leads under pressure with the cutting bladeof said cutting die from the side of the mounted face of the leads.